Okay, so abortion (among other topics) is something that has consistently been condemned in Church teaching since its beginning, and infallibly defined as morally evil.
You’re right about that.
We will not find such a thing for capital punishment
.
Of course not. Because there are times when it is just and necessary to apply the death penalty.
Capital punishment was openly practiced through the entirety of the past two millenniums in Christian lands, and continues to be practiced some today. There didn’t seem to be a huge outcry from the Church with that, or if there was, it was a peep compared to its firmness on other issues.
Because it’s largely an issue of prudence for when to apply capital punishment, since it’s not in and of itself wrong. You will find instances of Church Fathers condemning the use of capital punishment, but not because they have a problem with it per se, but because of the way it’s being used. Once states became Christian, there became much less of a problem with its usage, because it was assumed Christian kings and princes would apply it in a prudent manner according to Catholic teaching. As society has become less Christian, we’ve started to hear more and more from the Church about the necessity to give up capital punishment.
However, taking a life is always an evil thing,
No. It’s always sad when a life has to be taken, and it’s best not to be taken if it isn’t necessary, but it is by no means always evil.
and in Catholic theology it only is made acceptable through the principle of double effect.
Not true with capital punishment. There is value in retribution and justice, the giving of what one deserves. Of course, the Church has and does ask that authorities show mercy toward aggressors. These two principles must be balanced by the use of prudent judgment.
So how is it that this view developed into a more firm stance against capital punishment today, when the technology to quarantine people is something that has been around for ages? If, let’s say, we fell into a dystopian future, would this cease to be much of an issue once again? How much of this is discretionary?
Let’s take a look at CCC 2267:
Assuming that the guilty party’s identity and responsibility have been fully determined, the traditional teaching of the Church does not exclude recourse to the death penalty, if this is the only possible way of effectively defending human lives against the unjust aggressor.
Pretty self explanatory. Just keep in mind that “defending human lives” doesn’t include merely physical defense, but also moral and spiritual defense as well. It’s a very short summary of Church teaching on capital punishment.
*If, however, non-lethal means are sufficient to defend and protect people’s safety from the aggressor, authority will limit itself to such means, as these are more in keeping with the concrete conditions of the common good and are more in conformity to the dignity of the human person. *
The Church asks that society not use capital punishment today because it better serves the common good with respect to understanding the sacredness of human life, something our modern liberal world has no understanding of. Just look at abortion, embryonic stem cell research on one hand, and on the other the use of torture or the death penalty for trivial reasons in less developed countries. By not using the death penalty in our modern world, we are better showing the dignity of the human person.
Today, in fact, as a consequence of the possibilities which the state has for effectively preventing crime, by rendering one who has committed an offense incapable of doing harm - without definitely taking away from him the possibility of redeeming himself - the cases in which the execution of the offender is an absolute necessity “are very rare, if not practically non-existent.”
Further shows the Church requesting the abolition of the death penalty, both for the good of society and the criminal.